Double negative cutting insert for tools for chip removing machining

A double negative cutting insert for chip removing machining, including a body of generally flat polygonal basic shape;

• the body having opposite top and bottom sides of identical shape, and eight transverse flank surfaces extending between top and bottom sides, wherein the polygonal shape is octagonal with eight obtuse-angle corners comprising four active cutting corners, and four inactive cutting corners;
• two of the flank surfaces approaching one another at each active cutting corner and spaced from one another by a pair of lands;
• each flank surface forming a major cutting edge at the top side and a major cutting edge at the bottom side, and each land forming a minor cutting edge at least at one of the top and bottom sides, wherein each active cutting corner at the top and bottom sides includes at least one major cutting edge and at least one minor cutting edge;
• each of the top and bottom sides including four upstanding supporting projections disposed adjacent respective inactive corners;
• each supporting projection including a planar top surface;
• the top surfaces of the supporting projections on the top side lying in a common plane oriented parallel to a neutral plane of the body disposed midway between the top and bottom sides;
• the top surfaces of the supporting projections on the bottom side lying in a common plane oriented parallel to the neutral plane;
• each of the top and bottom sides including areas disposed at each active corner between respective pairs of adjacent supporting projections, the areas comprising concave lands to provide a positive cutting geometry during cutting operations.